Marquez-Farias: Length at maturity of the Squatina californica in the Gulf of California in Mexico 361 
Frequency 
Total length (cm) 
B 
olmmature 
= Mature 
Pregnant 
> 
oO 
(= 
o 
=] 
lox 
oO 
_ 
LL 
om eo) 
ae Se 
ow Oo 
oOo WoO © 
Total length (cm 
Frequency 
Total length (cm 
Figure 2 
Length-frequency distributions (A) by sex and by matu- 
rity stage for (B) female and (C) male Pacific angel sharks 
(Squatina californica) captured from the eastern Gulf of 
California in Mexico between 1998 and 2005. 
differences in mean length by sex for the Pacific angel 
sharks captured in the GOC (Mann—Whitney test: 
U=26,818, P=0.001). The mean length for mature females 
was 84.83 cm TL (SD 4.83) with a range of 75-100 cm TL 
(number of specimens [n]=114). The diameters of the larg- 
est oocytes were 20-60 mm and, in pregnant females, 
ranged between 26 and 50 mm (Fig. 3A). The mean length 
of mature males was 86.18 cm TL (SD 5.54) with a range 
of 73-99 cm TL (n=78); clasper lengths ranged from 10 to 
30 mm (Fig. 3B). Length ranges and maturity condition by 
sex are presented in Table 1 and Figure 4. 
The analysis of covariance from the binary logistic 
regression revealed a significant effect of sex (y7=14.9, 
Oocyte diameter (mm) 
0 
50 
Total length (cm) 
Clasper length (cm) 
50 
Total length (cm) 
Figure 3 
The relationship between total length and (A) maximum 
oocyte diameter and (B) clasper length for female and 
male Pacific angel sharks (Squatina californica), respec- 
tively, captured from the eastern Gulf of California in 
Mexico during 1998-2005. Open circles indicate immature 
individuals, black circles represent mature individuals, 
and open triangles indicate pregnant females. 
df=1, P<0.001). The model explained 75.0% of the vari- 
ance. The contribution of TL to variance was 71.5%, and 
sex explained 3.7% of the variance. The coefficients of the 
binary logistic regression for females (a=—51.95, b=0.698) 
were used in the logistic function to describe the estimated 
proportion of mature fish by length. For females, the L;o 
was 74.41 cm TL (95% CI: 72.81—76.00 cm TL), and the ® 
was 1.43 (95% CI: 0.84-2.42) (Fig. 5A). For males, the 
regression coefficients (a=—25.27, b=0.3247) yielded a L; 
of 77.82 cm TL (95% CI: 75.66-79.97 cm TL) and a ® of 
3.08 (95% CI: 1.98—4.77) (Fig. 5B). 
Discussion 
The results of this study, conducted on the coasts of Sonora 
and Sinaloa, indicate differences between the lengths of 
Pacific angel sharks in the GOC and those of individuals 
along the Pacific coast of the BCP. In general, individuals 
from the Pacific coast of the BCP grow larger than those 
